HIV-1 encodes 15 different proteins, yet current drug therapies target only 2 of these 15 proteins (HIV Protease and Reverse Transcriptase). Targeting additional HIV-1 proteins is an important strategy in the continuing battle against AIDS. Three Specific Aims proposed in this project are 1) Discover peptides, through a combinatorial phage-display approach, which bind with high affinity to the HIV-1 Vpu protein; 2) Determine the high resolution NMR structure of one or more of the Vpu-binding peptides; 3) Determine the NMR structure of the corresponding peptide binding site on Vpu with bound peptide. Phage display will allow rapid screening of many millions of different peptides to identify those which bind Vpu tightly, and which may be antagonists of Vpu-protein interactions which occur in HIV-infected cells. The structure of high-affinity Vpu-binding peptide(s), as fusion proteins with the bacteriophage pVIII protein, will be determined using NMR methods pioneered in the Opella laboratory. The structure of the non-transmembrane portion of Vpu (Vpu 28-81), with bound high-affinity peptide, will be determined using solution NMR methods. This may provide valuable information to direct the rational design of a new class of Vpu-targeting, anti-HIV drugs. Importantly, the methods developed during this project will also be widely applicable to drug discovery research involving many other diseases.